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Abstract:
While it has been widely assumed that punctuation may play a
critical role in parsing, there has been relatively little direct
empirical investigation of its effects. Most researchers have
either avoided the use of punctuation or have simply assumed that
it will serve a disambiguating role. There has been little or no
consideration of how 'disambiguation' might occur or whether it
is equally effective across different structures. Previous work
using self-paced reading (Hill and Murray, 1997) has in fact
shown that simplistic conclusions related to the role of
punctuation are unlikely to be supported. These studies showed
that while punctuation can play a potent disambiguating role in
some structures, the effect is by no means universal.
These conclusions, however, depend on the assumption that
punctuation acts in the same way with word-by-word self-paced
reading as it does in more natural reading tasks. The studies
reported here therefore extended this work by the monitoring of
subjects' eye movements while reading three types of locally
ambiguous items with and without inserted punctuation. Since
results from an earlier pilot study showed effects of punctuation
on saccade length, an additional condition of increased spacing,
without punctuation, was also included.
The results showed potent effects of punctuation on first pass
'garden pathing' in two structures (early closure and reduced
relative clause sentences), but not in sentences with
prepositional phrase ambiguities. Punctuation also had effects on
local processing difficulty, suggesting that it can cue some
types of parsing decision at particular points in a sentence. A
frequent effect of inserted punctuation was to increase
processing time on sections of a sentence immediately preceding a
comma, while facilitating processing which followed. Punctuation
and increased spacing between words had similar effects on
saccade length into a region, increasing these by more than the
added character space, but while spacing manipulations did
impinge on reading time, they did not have an equivalent
disambiguating effect. Punctuation therefore appears to convey
information related to structure that is more potent than the
simple 'chunking' of text, but this effect is limited to
particular structural conditions. Interestingly, there was little
effect of punctuation when it was consistent with a 'preferred'
parse. Its role appears to be more closely related to the
avoidance (in some circumstances) of incorrect decisions.
Hill, R.L. and Murray, W.S. (1997) Punctuated Parsing:
Signposts along the Garden Path. CUNY Sentence Processing
Conference, Santa Monica.
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